<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<script type="text/javascript">
		
	var a = 'ajsdjalkjds';
	//dja
	//JA
	//Ja
	alert(a.substring(3,6).substr(1,2).toUpperCase().replace('A','a'));
	
</script>
</body>
</html>